Saturable core circuits for counting and the like



Jan. 17, 1956 J. G. MILES 2,731,203

SATURABLE CORE CIRCUITS FOR COUNTING AND THE LIKE 2 Sheets-Sheet 1 FiledMay 24, 1951 STAGE I INVENTOR JAMES G. MILES FEEIDB 3 A C Z? WINDING OTRIGGIERAFWINDING ATTORNEY J. G. MILES Jan. 17, 1956 SATURABLE CORECIRCUITS FOR COUNTING AND THE LIKE Filed May 24, 1951 2 Sheets-Sheet 2A.C. POWER SOURCE INVENTOR JAMES G. MILES Isa/[W ATTORNEYS United StatesPatent SATURABLE CORE CIRCUITS FOR COUNTING AND THE LIKE James G. Miles,Minneapolis, Minn., assignor, by rnesne assignments, to Sperry RandCorporation, New York, N. Y., a corporation of Delaware Application May24, 1951, Serial No. 227,962

19 Claims. (Cl. 235-92) The present invention relates to magnetic coretype circuits adapted for use in binary counting circuits and the like.

Several magnetic arrangements are presently known for performingelectrical functions such as counting, amplifying, controlling ortriggering in computing machinery and control systems. One such deviceis disclosed in United States Patent No. 2,519,513 issued to R. L.Thompson. Patent No. 2,519,513 discloses a circuit in which anelectrical counting operation, theretofore performed by vacuum tubes, isaccomplished by means of saturable core reactors. The arrangement ofthat patent is chiefly concerned with apparatus generally consisting oftwo sections each having two conditions of stability, the sections beingcross-connected so as to provide an arrangement in which a change in thestability condition of one section will produce an opposite change inthe stability condition of the other section. In this respect, thedevice disclosed in Patent No. 2,519,513 is a magnetic analogue of thewell-known Eccles-Jordan flipfiop circuit. The Eccles-Jordan circuitessentially comprises two triode vacuum amplifiers regenerativelyconnected through resistors and condensers so that either one tube orthe other tube is always conducting. The Thompson device may be said toresemble the Eccles- Jordan flip-flop circuit insofar as it is also atwo-sided circuit with cross feedback, having two stable states, thesusceptance state of each side of the circuit being determined by thestate of the other side, and either one reactor section or the otherconducting at any instant of stable operation.

The present invention differs from the above and other devicespreviously known by reason of its greater simplicity and economy ofcircuit elements and also in the manner of its operation. The presentinvention is characterized, for example, by provision of a single-sidedmagnetic circuit with relay action in which the stability condition isself-determining according to an arrangement by which a considerableamount of the output signal of each subsection, or stage, is positivelyfed back into the same stage. The use of the positive external feedbackprinciple to obtain a plurality of conditions of stability is shown inUnited States Patent No. 2,027,312, issued to A. S. Fitzgerald. However,Patent 2,027,312 does not suggest any means for providing triggering andcounting properties such as those which form important features of thepresent invention.

An advantage of the present invention is that it permits the utilizationof a single-sided magnetic flip-flop that permits utilization of theattendant advantages of such single-sided flip-flop. One advantage ofemploying single-sided flip-flops is that there is no requirement forapproximately equal loads to optimize operational characteristics as isrequired by balanced or Eccles-Jordan type flip-flops.

Another advantage of the single-sided flip-flop is that it utilizesfewer core windings and circuit components than do balanced orEccles-Jordan type flip-flops. Singlesided flip-flops are thereforecapable of significantly faster operation, which is yet anotheradvantage in digital computer applications.

A distinguishing feature of the present invention is that the electricalcondition of a magnetic amplifier may be caused to advance from onestate of stability to the other by the application of unidirectionalpulses to a trigger ringing circuit.

It is therefore an object of this invention to provide a noveltriggering circuit in a magnetic flip-flop circuit.

It is a further object of this invention to provide a novel triggeringcircuit as described hereinafter, so constituted that its application toa conventional magnetic flip-flop circuit produces a device capable ofperforming a binary counting operation.

It is a further object of this invention to provide a magnetic flip-flopcircuit in which the electrical equilibrium is altered by a change inthe degree of core saturation of a magnetic element therein.

It is another object of this invention to provide a binary countingcircuit in which greater reliability is attained through the employmentof saturable core reactors in place of conventional vacuum tubes.

It is a further object of this invention to provide a binary countingcircuit of the saturable reactor type utilizing fewer core windings thanheretofore used.

Another object of this invention is to provide a binary counting circuitcapable of more rapid operation than hitherto possible.

It is yet another object of this invention to provide a binary counterof single-sided circuit form in which either of two conditions ofstability may obtain, such condition of stability being self-determinedas hereinafter set forth.

A still further object of this invention is to provide a binary countingcircuit in which the counter is advanced by means of a special triggerringing circuit as described below.

Further objects and the entire scope of the invention will becomefurther apparent in the following detailed description and in theappended claims. The accompanying drawings display the generalconstruction and operational principles of the invention; itis to beunderstood, however, that said drawings are furnished only by way ofillustration and not in limitation thereof.

In the drawings:

Figure 1 is a circuit diagram of a preferred form or embodiment of thisinvention.

Figure 1A is a circuit diagram of an alternative embodiment of theinvention shown in Figure 1.

Figure 2 is a graphical representation of the relationship between themagnetornotive forces present in a trigger winding and an externalfeedback winding of a saturable core reactor element in the counter.

Figure 3 is a graphical representation of the waveforms present atcertain specified points with reference to Figure l.

A preferred circuit embodying the various features of the presentinvention is shown in Figure 1. Figure 1 shows two stages of a magneticbinary counter, the stages being designated as I and II by legend inFigure 1.

Referring to Stage I, there is provided a toroidal core 10 composed forexample of spirally-wound molybdenum permalloy tape. On this core thereis disposed a trigger ringing winding 12, a reactance winding 14 and afeedback winding 16.

An input such as a pulse input is intended to be applied between asuitable ground connection and a terminal 18. The input may, if desired,be provided with a resistance 19 connected from terminal 18 to ground.From terminal 18 the input pulse is applied to the trigger winding 12through a capacitance 20 connected in lead 22.

The reactance winding 14 is connected over a line 24 and through adecoupling capacitance 26 to a suitable source of alternating currentpower 28. The source 2% will preferably be an R. F. source, as will beexplained more fully hereinbelow.

The feedback winding 16 is connected over leads 36 and 32 (and othercircuit elements to be described below) to the direct current terminals34 and 36, respectively, of a full wave rectifying circuit designatedgenerally as The alternating current terminals 40 and 42 of therectifier 38 are connected between ground at terminal 42 and at terminal4-0 to a point in an alternating current circuit comprising thereactance coil 14 and power source 28.

The circuit as thus far described may function with the single core 10by providing in the D. C. circuit between rectifier 38 and feedback coil16 a suitable R. F. choke to block the flow of R. F. currents in thiscircuit. Also the circuit comprising the trigger ringing coil 12 may beprovided with a suitable R. F. choke to block R. F. currents in thatcircuit.

A representative circuit utilizing chokes is shown in Figure 1A. Thiscircuit closely follows either one of stages I and II as shown inFigure 1. it will be noted that the power source supplies alternatingcurrent through the capacitance 26 to the reactance winding 14.Connected to the opposite end of winding 14 is the bridge rectifier 38.The feedback winding 16 is connected at one end thereof to one D. C.terminal of bridge 33 as is the case in Figure 1. However, the oppositeend of feedback Winding 16 instead of going to a coil on a companionsaturable reactor is connected to a suitable choke 16' and from thereproceeds to the second D. C. terminal of the bridge 38. Thus thealternating current which may be induced in the feedback winding 16 bytransformer action from the reactance winding 14 is blocked in thefeedback circuit. Similarly, whatever alternating currents which may beinduced in the trigger winding 12 by reason of transformer action areblocked by suitable choke 12.

However, while chokes may be employed as mentioned in the immediatelypreceding paragraph, it is preferable, as shown in Figure 1, to employ asecond toroidal core ltlA which is identical with core 10. About core16A there are also provided windings 12A, 14A, and 16A which may beidentical in all respects to the windings 12, 14, and 16 on core 10. Thefunction of core 10A and the windings thereabout is to effectivelycancel objectionable R. F. currents in the trigger ringing and feedbackcircuits and to thereby replace the previously mentioned chokes and withimproved results. As indicated in Figure 1, the direction of winding ofeach of the respective trigger and feedback windings only corresponds oneach of the cores so that the relationships of the M. M. F.s produced byeach of the trigger and feedback windings on each core will be the same.Reactance windings are wound in opposition to provide theabove-mentioned decoupling of the control and feedback circuits from theA. C. power supply circuit, as is well known in the art.

In addition to the use of two separate toroidal cores for cancelling outundesired alternating currents, there may be employed, for example, asingle core of the following type: The core may be built up as bystacked laminations having two outer legs at the ends of the core with athird leg of considerable cross-section between the outer legs, thisthird leg being subdivided in its central portion to form two parallelsub-legs of reduced crosssection. This type of core construction hasbeen previously known in the art as for example in Patent 2,027,312,referred to above. For use with the present invention, the two reactancewindings will be each wound on one of the just-mentioned sub-legs andconnected in 1 of the S series but wound in opposite directions. Thetrigger winding may then be wound completely about the central thirdleg. The feedback winding is also wound about the third central leg.

Those skilled in the art will understand from the foregoing descriptionthat alternating current in the reactance winding 14 will produce apredetermined alternating flux in the core 10. Also, the connection ofterminal 40 of the rectifier 38 in a lead 44 leading from winding 14A,which latter is in turn connected over lead 46 with winding 14, willcause a direct current of predetermined value to flow through thefeedback windings 16 and 16A which windings are connected in series withthe direct current terminals 34 and 36 of rectifier 38. The arrangementis such that, assuming the current in winding 14 to be subject to a fluxin an intermediate amplitude, a change in the inductive reactance ofcoils 14 and 14A will cause a change in the R. F. voltage at terminal 40of rectifier 38 which will result in a change in direct current throughcoil 16 to alter the stability of the circuit in a manner to bedescribed fully hereinbelow. As will become apparent, the windings 16and 16A are in positive feedback relationship with the trigger windings12 and 12A respectively when the trigger windings are conducting apositive impulse.

Continuing to refer to stage I of Figure 1, the capacitance 2t? and theinductive reactance of winding 12 and return impedance 19 form a seriesresonant circuit which can be shock-excited, or caused to oscillateelectrically, by the application of a single impulse of electric energyas at terminal 18 across the impedance 19 to ground. However, because ofdamping due in part to the ohmic resistance of the winding 12, there canbe but substan tially one positive and one negative surge of current.Thus by this arrangement there is provided a means whereby a successionof unidirectional input pulses such as counting pulses may producecritically damped ringing oscillations. As will be explained below, thejust-mentioned surges of critically damped oscillating current throughthe winding 12 will contribute to altering the flux conditions withinthe core 10 (and the core 10A if .employed) to cause the circuit toassume one of two conditions of magnetic and electrical stability, thatis, either relatively direct current saturation or relatively directcurrent non-saturation. Hereinbelow it will be assumed that two coresare employed.

Assuming that suitable values of frequency and voltage are applied torender the circuit operable, alternating current from the power source28 passes through the re actance windings and the rectifier, andunidirectional (rectified) pulsating current then exists in the feedbackwindings. The feedback current causes the cores to be partiallysaturated. This degree of saturation, and other magnetic and electriceffects to be described hereinafter, may be best understood withreference to the graph in Figure 2.

The graph in Figure 2 illustrates the relationship between themagnetomotive forces (M. M. Ffs) of the trigger windings and thefeedback windings where the A. C. source voltage and frequency remainconstant. The curve AKBMCDNEF forms a so-called 8 curve common tosaturable core devices having excessive regenerative f edback, as willbe well understood by those skilled in the The line ED is verticallytangent to the upper knee curve at point D, and the line CE isvertically tangent to the lower knee of the 3 curve at point C. Theknees of the S curve represent the limits of the unstable region DC.

The previously mentioned feedback current in the feedback windingscauses the cores to be partly saturated. It may be first assumed thatthe core is at a lower stable state of saturation at stability residualpoint M of the curve in Figure 2. As an approach is made towardsaturation, as by adding saturating M..M. F. from the trigger ringingwinding or any other means, the incremental permeability, the etfectiveinductance, and therefore the inductive reactance of the reactancewinding '14 and the 1 feedback Winding 16 decreases in a manner wellunderstood by those skilled in the art until a critical point C isreached. At this time the feedback current increases 5 sharply to excitethe core proportionately further towards saturation, and the feedback M.M. F. rises along the path CE and thence along EF, where inductance isat -a low value and the feedback M. M. F. is sufiicient to keep the corein a state of upper or saturated stability. The upper position ofstability is somewhere along the line DEF, preferably at N.

A lower or desaturated condition of stability will obtain if by somemeans there is induced an M. M. F. tending to partially cancel thefeedback M. M. F. The cores will then become less saturated, feedback M.M. F. will decrease along the path FED in Figure 2 and the effectiveinductance and therefore reactance will increase until a critical pointD is reached. From point D the feedback M. M. F. will fall off sharplyalong the line DB, thus going proportionately further into desaturation.The cores thereby stabilize at point M, the previously mentioned stateof lower or desaturated stability at which the inductance is at a highvalue and the feedback M. M. F. is relatively small.

The manner in which the ringing oscillations are employed to effect achange in the just-mentioned magnetic equilibrium will now be explainedin detail: If the cores are in an upper or saturated condition ofstability at N along the curve DF the M. M. F. produced by the positivesurge of the ringing current will merely drive the cores further intosaturation. The ringing M. M. F. is represented in Figure 2 by the curveextending through the points G and H, this curve being characterized byswings to one side and then the other of a vertical line passingsubstantially mid-way between the critical points C and D. The swings topoints G and H exceed the points C and D, as indicated.

While the positive surge including the point G will be ineffective inchanging the state of the circuit, nevertheless, the negative surgepassing through point H and therefore going below the point D will drivethe cores into the lower or desaturated stability condition along thepath NDBKBM. When the negative part of the trigger pulse is removed,lower stability will settle at M. If now another positive input pulse isapplied the positive surge including point G will exceed point C andwill drive the cores into a saturated condition along the path MCEF.While a negative surge including the point H will follow the positivesurge this negative surge will not operate to immediately force thecircuit back into the lower condition of stability. The magnetic inertiaof the system as it snaps into the region of upper stability along thepath CEF prevents the rapidly following negative surge H from forcingthe cores back into the lower state. Circuits according to thisinvention have been built and operated extensively and function in themanner set forth herein.

From the foregoing description it will be clear that a so-calledsingle-sided flip-flop is provided. While two cores 1i? and 10A areemployed in the preferred embodiment, the device remains a single-sidedflip-flop, inasmuch as the second core 10A is employed only forcancelling R. F. currents and is not interconnected with the first one10 in any manner resembling a circuit analogous to an Eccles-lordancircuit.

While I have described my novel trigger ringing circuit as employed witha single-sided flip-flop stage according to the herein invention, itwill be apparent that my trigger ringing circuit may also be employed totrigger two-sided flip-flop circuits as well.

A preferred means of obtaining an output signal from the flip-flop stagemay be by sampling the voltage appearing across the alternating currentterminals 40 and 42 of the rectifying circuit 38. The-forward impedanceof the 75 rectifier is suflicient to load' the flip-flop stage itself.The voltage waveform appearing across the rectifier terminals 40 and 42will be analogous to the wave form of an amplitude-modulatedradio-frequency signal in that the voltage amplitude of this modulatedalternating current wave form will be large when the flip-flop is in theupper region of stability and small when the flip-flop is in the lowerregion of stability.

Wave forms resulting from the operation of the circuits as thus fardescribed may be fully understood with reference to Figure 3. In Figure3, various wave forms are indicated in parts (a) through (h) of thisfigure, successive Wave forms occurring at times to through t4. Positiveinput pulses applied to terminal 18 are represented in part (a) ofFigure 3. Figure 3 part (b) represents the ringing oscillations whichoccur in windings 12 resulting from the application of the input pulses,and part (c) represents the modulated wave form of the alternatingvoltage appearing at terminal 40 of the rectifier 38. Still referring toFigure 3, parts (a), (b), and (c) serve to make clear that an inputpulse applied in terminal 18 at time t1 will cause the wave formenvelope to be of maximum amplitude until the occurrence of the nextinput pulse at time t2 when the envelope will become reduced to smallamplitude until the next input occurs at time t3 and so forth.

Inasmuch as the signal sampled across terminals 40 and 42 of rectifier38 will be a modulated alternating voltage, a useful pulse outputvoltage may be readily obtained in the following manner: Continuing torefer to Figure 3 and also referring to Figure 1, detection may beaccomplished by connecting terminal 40 of rectifier 38 over a line 48 toa clipping section comprising resistance 50 connected between line 48and ground, a second resistance 52 also connected to ground, and acrystal diode 54 connected between line 43 and the ungrounded end ofresistance 52. The function of the clipping section is to transmit onlythe lower or negative portion of the wave form envelope, as representedin part (c) of Figure 3. The lower negative side of the envelope asillustrated in part (at) of Figure 3 may then be demodulated bycondenser 56 connected in parallel to ground with resistor 52. Theaction of capacitor 56 will be to eliminate the alternating voltage toproduce a square wave form as represented in part (c) of Figure 3.

One use for the direct current output signal just described may be togenerate a carry pulse to be used as an input pulse to a next succeedingflip-lop stage as in a binary counter. For this purpose aresistor-capacitor differentiating circuit comprising resistance 58 andcapacitor 60 may be connected between the ungrounded side of capacitor56 and ground as shown in Figure l to differentiate the output squarewave shown in part e of Figure 3, producing first a negative and then apositive pulse for each square wave cycle. The resulting negative andpositive pulses are represented in part (f) of Figure 3. Since only onepulse is required for each counting cycle in a binary counting circuitthe positive pulse may be chosen arbitrarily to be clipped by a crystaldiode 62 connected, as shown in Figure 1, in parallel to ground with theresistor 58. The remaining negative pulse as illustrated in part (g) ofFigure 3 is the carry pulse from the counter stage. This carry pulse maybe inverted and matched into the trigger ringing circuit of the counterstage II by means of an impedance matching pulse transformer 64, asshown in Figure l. The output of transformer 64 appears on line 66,which may be termed the carry line and this wave form is represented inpart (h) of Figure 3.

Stage Ii of the counter may be in all respects identical with stage I,as shown in the drawings, and will in turn serve to produce an outputpulse on its output line designated 66 for every other input pulsereceived over line 66. From the foregoing and with particular referenceto Figure 3, it will be apparent that each stage will produce a singleoutput pulse for every second input pulse and therefore the stages asinterconnected Will perform as a binary counting circuit.

Magnetic binary counters with supply frequencies of 1.0 megacycle havebeen constructed and operated at rates as high as 60,000 counts persecond and even this rate is not by any means a maximum rate.

While those skilled in the art will understand that a great manycombinations of values of the various components of the circuitshereinabove described may be em- Power source 28: l megacycle Toroz'dalcres.-The cores should have the smallest possible amount of corematerial in order that their magnetic state may be changed rapidly withonly a small amount of energy. Therefore, it is preferable that thecores of Figure 1 be made of a sensitive magnetic material, as forexample, 4-79 molybdenum permalloy tape about /8 mil thick and aboutinches Wide. The tape may be insulated by a colloidal deposition appliedby a cataphoresis method. Ten turns of the insulated tape may bespirally wound under tension on a ceramic mandrel to form a suitablecore.

It will be understood that the foregoing values and speci ications aremerely illustrative and it is not intended that the herein invention belimited to these values. Since other values and other embodiments of theinvention will become apparent to others upon reading thisspecification, it is intended that the invention be limited only by thescope of the appended claims.

I claim:

1. In a device having a saturable core, a reactance winding and afeedback winding arranged on the core, means connected with the windingsfor supplying electric current thereto so that the device has first andsecond critical states of flux saturation in the core beyond which thedevice Will drive itself to first and second stable states, triggeringmeans for shifting the circuit from either stable state to the other,the triggering means comprising a triggering winding on the core, thetrigger-Winding being connected with a capacitance in a resonantcircuit, and means for causing the flow of an oscillatory surge ofelectric current through the triggering winding, the oscillation beingof sufiicient magnitude to drive the core flux beyond either one of thecritical states and into the opposite stable state.

2. In a device having a saturable core, a reactance winding and afeedback winding arranged on the core, means connected with the windingsfor supplying electric current thereto so that the device has first andsecond critical states of flux saturation in the core beyond which thedevice will drive itself to first and second stable states, triggeringmeans for shifting the circuit from either stable state to the other,the triggering means comprising a triggering winding on the core, thetrigger winding being connected with a capacitance in a resonantcircuit, and means for causing the flow of an electric excitationcurrent oscillation consisting of a current surge in a first directionfollowed by a current surge in a second direction through the triggeringwinding, the surges being of sufficient magnitude to drive the core fluxbeyond either one of the critical states and into the opposite stablestate.

3. In a device having a saturable core, a reactance Winding and afeedback winding arranged on the core, means connected with the windingsfor supplying electric current thereto so that the device has first andsecond critical states of flux saturation in the core beyond which thedevice will drive itself to first and second stable states, triggeringmeans for shifting the circuit from either stable state to the other,the triggering means comprising a triggering winding on the core, thetrigger winding being connected with a capacitance in a resonantcircuit, and means for causing the flow of an electric excitationcurrent oscillation consisting of a current surge in a first directionclosely followed by a current surge in a second direction through thetriggering winding, the surges being of sufficient magnitude to drivethe core flux beyond either one of the critical states and into theopposite stable state.

4. In a device having a saturable core, a reactance winding and afeedback winding arranged on the core, means connected with the windingsfor supplying electric current thereto so that the device has first andsecond critical states of flux saturation in the core beyond which thecircuit will drive itself to first and second stable states, triggeringmeans for shifting the device from either stable state to the other, thetriggering means comprising a triggering Winding on the core, thetrigger winding being connected with a capacitance in a resonantcircuit, and means for causing the flow of an electric excitationcurrent oscillation consisting of a current surge in a first directionclosely followed by a current surge in a second direction through thetriggering winding, the surges being of suflicient magnitude to drivethe core flux beyond either one of the critical states and into theopposite stable state, the time duration of the surges beingsufiiciently short relative to the shifting time of the circuit toprevent reshifting of the circuit in response to a surge immediatelyfollowing the shifting surge.

5. Apparatus as in claim 1 and further including means connected withthe reactance winding for obtaining a signal indicative of the stablestate of the circuit at any given time.

6. Apparatus as in claim 5 wherein the stable state indicating signal isan alternating current of one of two amplitude levels depending on thestable state at a given time, and wherein means are provided forclipping, demodulating and differentiating the indicating signal toderive a single carry pulse for every second excitation currentoscillation in the trigger winding.

7. Apparatus as in claim 1 and further including means interconnectingthe reactance and feedback windings for obtaining a signal indicative ofthe stable state of the circuit at any given time.

8. Apparatus as in claim 4 and further including means connected withthe reactance Winding for obtaining a signal indicative of the stablestate of the circuit at any given time.

n eluding means interconnecting the reactance and feedback windings forobtaining a signal indicative of the stable state of the circuit at anygiven time.

11. Apparatus as in claim 10 wherein the means interconnecting thereactance and feedback windings cornprises a rectifying circuit.

12. Apparatus as in claim 7 wherein the means interconnecting thereactance and feedback windings comprises a rectifying circuit.

13. Apparatus as in claim 1 and further including means for applyingonly unidirectional excitation pulses to the resonant circuit.

14. Apparatus as in claim 4 and further including means for applyingonly unidirectional excitation pulses to the resonant circuit.

15. A binary counting circuit made up of interconnected stages, eachstage comprising a reactance winding and a feedback winding arranged ona saturable core, means connected with the windings for supplyingelectric current thereto so that the stage has first and second criticalstates of flux saturation in the core beyond which the circuit willdrive itself to first and second stable states, triggering means forshifting the circuit from either stable state to the other, thetriggering means comprising a triggering winding on the core, thetrigger winding being connected with a capacitance in a resonantcircuit, means for causing the flow of an electric excitation currentoscillation consisting of a current surge in a first direction closelyfollowed by a current surge in a second direction through the triggeringwinding, the surges being of suflicient magnitude to drive the core fluxbeyond one of the critical states, the time duration of the surges beingsufiiciently short relative to the shifting time of the circuit toprevent reshifting of the circuit in response to a surge immediatelyfollowing the shifting surge, means connected with the reactance windingfor providing an alternating voltage envelope the amplitude of whichindicates the stable state of the stage, means comprising means fordemodulating the voltage envelope to obtain an indicating signal uponthe occurrence of a transition of the stage, and means forinterconnecting the just mentioned means of the first stage to theresonant circuit means of the next following stage to trigger said nextstage in corresponding manner.

16. A circuit as in claim 15 wherein the means for obtaining anindicating signal also comprises diflferentiating and clipping means forproducing a single unidirectional pulse for every second transition ofthe stage.

17. In a saturable core device having first and second stable states,triggering means for shifting the device from either stable state to theother, the triggering means comprising triggering winding meansconnected with capacitance means in a resonant circuit, the resonantcircuit including parameters for damping same so that an excitationpulse applied thereto will cause substantially only a single oscillationin the triggering winding means.

18. In a binary counting circuit made up of interconnected stages ofsaturable core devices wherein each device has a reactance winding, aninterconnected feedback winding and a damped resonant trigger windingcircuit, means operatively connected with the reactance winding forobtaining an output in the form of an envelope of alternating voltagethe amplitude of which indicates the stable state of the stage, andmeans for obtaining a carry pulse for operating the next stage, saidcarry pulse means comprising means to demodulate the alternating voltageenvelope.

19. A circuit as in claim 18 wherein the carry pulse means furthercomprises means for differentiating the Wave form obtained bydemodulation, and further comprises means for suppressing one of thediiferentiated pulses so as to provide a single carry pulse for everysecond transition of a stage.

References Cited in the file of this patent UNITED STATES PATENTS1,862,211 Dowling June 7, 1932 2,010,610 Simpson Aug. 6, 1935 2,010,614Suits Aug. 6, 1935 2,027,312 Fitzgerald Ian. 7, 1936 2,222,048 Stevenset al. Nov. 19, 1940 2,265,296 Lee Dec. 9, 1941 2,519,513 Thompson Aug.22, 1950 2,524,154 Wood Oct. 3, 1950 2,591,406 Carter et al. Apr. 1,1952 2,640,164 Giel et al May 26, 1953 OTHER REFERENCES Static MagneticStorage and Delay Line, An Wang and Way Dong Woo; Journal of AppliedPhysics, volume 21, January 1950; pp. 49-54.

